The property dates back to 1870, and features a total of 30 letting bedrooms, nine of which are situated in the adjacent Castle Lodge building.
The seller is also accepting offers for Knock Castle and Castle Lodge individually, for asking prices of £1.25m and £500,000, respectively.
The site sits within three and a half acres of gardens and woodland and features a lower ground spa, as well as a rooftop terrace and restaurant which offers views of the Strathearn Valley.
The business is well recognised as a wedding venue, as well as leisure and spa breaks and conference meetings.
A self-contained pool and leisure club feature, as well as two function suites that are used for small meetings, weddings or gala dinners. The residents’ cinema can also be used for small meetings of up to 12 people.
The sale includes two additional two-bedroom flats, one in the main hotel building and the other in Castle Lodge, which can be used as staff accommodation.
Brian Sheldon, regional director, Scotland, at Christie and Co, who is handling the sale, said: “This presents a great opportunity for the discerning buyer to further enhance this established business and increase income and profit.”